Incontinence is a condition suffered by many patients in facilities such as nursing homes, acute care facilities, and intensive care units (ICUs). The traditional solution has been to clothe patients in diapers. Commonly, patients are not changed frequently enough. Continued contact of the skin with body waste leads to complications such as Incontinence-Associated Dermatitis (IAD), known familiarly as “diaper rash.” IAD can further develop into pressure ulcer (PU) and other secondary skin infections. According to Changing Our Methods of Adult Incontinence Management to Decrease Skin Breakdown and Improve Patient Satisfaction, 42nd Wound, Ostomy & Continence Nurses Society Conference, Jun. 12-16, 2010, 78% of acute-care hospitalized adult patients wearing diapers suffered from these conditions. Among incontinence patients in residential care facilities, half were urinary incontinent only, according a CDC Study, Prevalence of Incontinence Among Older Americans, CDC Vital And Health Statistics, June, 2014. The same Study also found that individuals who are incontinent may carry an emotional burden of shame and embarrassment in addition to the physical discomfort and disruption of their lives that occur with episodes of incontinence.
Major metropolitan hospitals have eliminated diapers in favor of underpads due to IAD. Underpads, disposable absorbent towels made with layered absorbent material, are preferable to diapers because they minimize the contact area between skin and waste that causes IAD. Incontinence hospital patients are now placed on underpads while wearing open-back gowns. Changing an underpad is simple in comparison to changing a diaper.
In as much as underpads are less likely to cause diaper rash than diapers because there is more room for air circulation, IAD is still a danger as long as there is prolonged exposure of the skin to urinary discharge. The timely changing of diapers and underpads is the cure for IAD. However, prior art systems have shortcomings in timely notification of staff.
For alert and demanding suffering patients, assistance call bells for each institutional bed would be activated. Depending on the staff ratio and the existing level of care at the facility, calls may or may not be responded to as timely as desired. Also, assistance calls are not specific on the nature and severity of the call, and nurses are usually the first responders. Incontinence is most economically handled by nurses' aides. A specific and automatic incontinence alarm can be more effective in-patient care, be it IAD or the psychological scourge of loss of dignity when incontinence is not handled expeditiously. Lower functioning patients may not even be aware of their incontinence to call for help.
Many approaches have been taken in the prior art to provide a sensor embedded in a multilayer absorbent article in order to indicate an incontinence event. In this manner, a patient can be attended to when there is a need rather than on a predetermined time schedule.
Prior approaches have been embodied primarily in diapers. A number of these approaches utilize radio frequency (RF) resonance, and recently, radio frequency identification (RFID) incorporating advances in this technology. RFID is familiar to consumers as the technology that permits vehicle owners of RFID identification devices to bypass toll booths and enter secured garages without stopping. RFID offers added identification capability to RF resonance detection. User and usage data can now be recorded and retrieved wirelessly. Most RFID systems continuously emit high frequency RF in the same manner as cell phones being left on to respond to incoming calls. Recent government reports correlate continuous cell phone usage with brain disease. An RFID system that does not require continuous radio frequency emissions eliminates or reduces concern as to this correlation.
An RFID tag primarily comprises an antenna and assorted electronic components to enable 2-way communication between tag and transceiver. A passive tag is not powered; but when its antenna resonates with a signal generated by its mating transceiver, the energy received powers on the tag integrated circuit to activate the tag. Passive RFID tags can be queried via a frequency with which the antenna is resonant. In response to excitation with a resonant frequency, the resonating antenna provides energy which can be stored in a capacitor which functions similar to a micro-miniature rechargeable battery. Passive RFID tags are more convenient to use than active, powered RFID tags because they do not depend on battery or external power to work and are suitable for reporting ID and other information.
Antenna impedance changes in the proximity of certain materials. An example is when the RFID tag is close to objects with high capacitance. A human body with its very high water content can detune both the RFID tag and the antenna. Most RFID tags of varying operating frequencies are affected by the proximity of the human body in the same manner. Thus, RFID sensor tags can use impedance change at its antenna to sense objects which induce changes in the antenna characteristics. Recent technical advances allow RFID tags to serve as sensors for certain material attributes rather than merely providing identification. Each type of RFID sensor tag is calibrated to the characteristics of a specific physical attribute such as moisture or temperature or gas or pressure, to name a few of the currently available types.
There is an RFID moisture sensor tag on the market that demonstrates on its web site (https://www.youtube.com/watch?v=meB9imQN0HU&feature=youtu.be) that the product can be used to detect wet diaper. The demonstration consists of pouring water on a dry diaper with a moisture sensor tag attached and a hand-held RFID reader to detect moisture reading. This video does not address the situation of a diaper on a real body. Because the human body holds enough moisture to trigger a “wet” reading when the dry diaper is wrapped around the patient, there will be false positive reading errors since body capacitance has not been factored out. This prior art system also requires a caregiver to tape a moisture sensor RFID tag on a diaper and periodically read the sensor output on bed inspection rounds unless the patient calls out for service before the manual scanning. Sanitation concerns will also mean that the sensor will be disposed along with the wet diaper.
United States Published Patent Application No. 20020145525 discloses a diaper comprising a plurality of RFID tags. Each of the RFID tags is coated with a dry electrolyte which enhances response to moisture. Each tag is also assigned a unique frequency. The sequence and relative response of tags to enquiring signals indicate position and moisture status. Because of the design complexity, implementation can be costly.
United States Published Patent Application No. 20140358099 discloses a system embedded in a diaper including first and second RFID tags respectively placed on an upper end and a lower end of a diaper with a moisture strip connected to both tags. This construction requires special fabrication to connect the RFID tags and the sensor. Standard, off-the-shelf components cannot be used.
U.S. Pat. No. 8,502,684 discloses a diaper with dissolvable conductive moisture sensor traces connected to an RFID tag antenna. Initial moisture contact will not completely dissolve the traces, and an antenna impedance change will indicate initial moisture. A positive incontinence condition is indicated by complete dissolution of the traces, with the RFID antenna not functioning. Lack of response is indistinguishable from a complete failure. Special materials must be used for the conductive traces to avoid breaks during handling and in in situ wearing conditions
U.S. Pat. No. 6,876,303 discloses a system for monitoring hospital personnel, a plurality of patient locations for patients and associated devices having a plurality of patient controls. Transmitters carried by each of a plurality of hospital personnel each periodically transmit a signal unique to that transmitter. The signal could indicate a patient or sensor triggered event alarm. A computer coupled to the associated devices is configured to respond to disable at least one of the patient controls while hospital personnel attend to the patient. This arrangement monitors hospital personnel and not patients nor their need status.
U.S. Pat. No. 8,237,572 and other patents, including U.S. Pat. No. 8,248,249 disclose an RFID tag and a system and method involving a plurality of RFID tags. Each RFID tag is attached to an object or to a structure or a person on which the presence of a predefined fluid is monitored. In a first state, absence of the monitored fluid, the tag is acting as a passive RFID tag and the information it holds can be read with a proximity RFID reader. This operation is performed when the RFID tag is attached to the object to be monitored. At this stage a table associating tag ID, object name and location may be built, and may be recorded so that information it contains is accessible by a control center. In a second state, whenever the monitored fluid appears on the tagged object, a fluid activated battery generates the electrical power which is used to power the RFID tag. The RFID tag then acts as an active RFID tag and starts to emit messages which can be received by a distant RFID reader. Alert messages include at least the tag ID but may comprise additional information like a name or a location. This system relies on activation of a battery by the salts in incontinence waste fluid which requires specially built components.
U.S. Pat. No. 8,196,809 discloses a system including a reader and an absorbent article containing machine-readable information identifying the user associated with the absorbent article and the user's location. A computer uploads data from the reader and stores the identifying information. On retrieval of information from the computer memory, information concerning the absorbent article is automatically associated with the identity and location of a user of the absorbent article. This disclosure is only concerned with inventory of the absorbent article; no live usage condition sensing is involved. This arrangement does not provide the benefit of monitoring the in situ status of the incontinence article as well as identification of its user and location.
United States Published Patent Application No. 20170224554 discloses a sensor system for detecting a property of or within an absorbent article which may comprise the absorbent article and a sensor. The sensor is a multi-use sensor for detecting the property. The sensor is configured for temporary attachment to and removal from the absorbent article, and still presents the difficulties of requiring custom assembly by medical staff.